A sock and spider web sit in a hole in a fence near the Vermont Street entrance to the closed 25th Street pedestrian bridge over Highway 101 in San Francisco, Calif. on Tuesday, July 1, 2014. The bridge has been closed for many years.

Evidence of a homeless camp and a notice to vacate an illegal campsite is taped onto a fance near the closed 25th Street pedestrian bridge over Highway 101 in San Francisco, Calif. on Tuesday, July 1, 2014. The bridge has been closed for many years and nearby residents report homeless people often camp on the bridge.

A sign in front of the closed 25th Street pedestrian bridge over Highway 101 directs people to a nearby bridge in San Francisco, Calif. on Tuesday, July 1, 2014. The 25th Street bridge has been closed for many years.

A notice to vacate an illegal campsite is taped to a fence near the closed 25th Street pedestrian bridge over Highway 101 in San Francisco, Calif. on Tuesday, July 1, 2014. The bridge has been closed for many years and nearby residents report homeless people often camp on the bridge.

Sandy Stone looks out from her Potrero Hill home at a footbridge over Highway 101 that's been closed to the public for more than 15 years.

Instead of offering Stone, her husband and their newborn a convenient thoroughfare between the neighborhood and the Mission District, the bridge at 25th Street has been chained up and allowed to deteriorate into a hangout for some of the area's less scrupulous residents.

Homeless camping, drug sales and prostitution, neighbors say, are just a few of the things happening inside or outside the bridge's locked gates.

The government agencies that have a say in managing the footbridge - which are several - recall that the overpass connecting Vermont and Kansas streets was shut down before 1999 for safety reasons. It had attracted criminal activity and had been used as an escape route for thieves and other miscreants trying to flee from police.

However, officials are loath to say if the closure has done anything to fix the problem, or has made matters worse - or might be worth revisiting.

Chronicle Watch first highlighted the problem in 2007. Caltrans, which has taken ultimate responsibility for access to the bridge, said then that it reviewed the situation and opted to keep the doors closed.

"The neighborhood seems pretty happy," a spokesman said in early 2008.

On Wednesday, another Caltrans spokesman, Bob Haus, said San Francisco police had asked the state agency to close the footbridge nearly 20 years ago.

"We haven't heard from them (and) I don't think anyone on our end has asked them to lift it," Haus said. "Nothing has really changed."

Figuring out who might re-evaluate the issue is a window into government bureaucracy. Stone said she's made numerous calls, but hasn't figured out exactly who can help her.

Public Works officials say they're responsible for maintaining the walkway on the bridge, but aren't in charge of the locks.

San Francisco police officials, meanwhile, said they hadn't been asked whether their 15-year-old concerns about public safety were still valid.

"It would take some asking around to see if there was someone in the Police Department to speak to about what was happening 15 years ago," said Capt. Robert O'Sullivan.

A police spokesman, Officer Albie Esparza, said he believed the bridge was closed after neighbors requested the move in a series of community meetings.

"I don't know what the issue was at the time," Esparza said. "This happened under an administration that have all since retired."

Today, not everyone sees a problem with the closure. A couple of neighbors said they remember the bridge being used by thieves to outrun police, and they're glad it was shut down.

Neighbor Anna Orkin said a lot has changed in the Mission and Potrero Hill neighborhoods over the last decade. She questioned whether the closure was still necessary.

Another person said he doesn't care if the bridge reopens but that someone should put an end to the loitering and shady activity there.

In the meantime, the neighborhood is left with a closed bridge and the sometimes irritating crowd that has set up shop there.

On a recent day, residents spoke of one man who has made the overpass his full-time living quarters, keeping bedding and clothing there and climbing over the fence each day to get in and out. He's often joined by others, they said.

Overgrown trees next to the walkway obscure blankets, shopping carts, liquor bottles and other debris.

Gretchen Petersen, who moved to the area in April, said she sees and hears about the ruckus by the bridge and wonders if things would be different if the walkway were opened.

"I would use it," she said. "It would be handy for us."

What's not working

Issue: A footbridge across Highway 101 in San Francisco's Potrero Hill has been closed at least 15 years because of public safety concerns but, according to neighbors, continues to be used for things like camping, drug use and prostitution.

What's been done: The Chronicle contacted several public agencies that have had a say in managing the footbridge, but none said they were taking steps to open it. In the past, Caltrans has opted to keep it closed - an option favored by some neighbors.